1. Field of the Invention
The present invention relates generally to the installation of mechanical splice connectors and verification of proper mechanical splice terminations, and more particularly, to an installation tool with an integrated visual fault indicator for a field-installable mechanical splice connector.
2. Technical Background
Optical fibers are useful in a wide variety of applications, including the telecommunications industry in which optical fibers are employed for voice, data and video transmission. Due, at least in part, to the extremely wide bandwidth and the low noise operation provided by optical fibers, the variety of applications in which optical fibers are being used is continuing to increase. For example, optical fibers no longer serve merely as a medium for long distance signal transmission, but are being increasingly routed directly to the home, and in some instances, directly to a desk or other work location. With the ever increasing and varied use of optical fibers, apparatus and methods have been developed for coupling optical fibers to one another outside the controlled environment of a factory setting, commonly referred to as “field installation” or “in the field,” such as in a telephone central office, in an office building, and in various types of outside plant terminals. However, in order to efficiently couple the optical signals transmitted by the fibers, a fiber optic connector must not significantly attenuate, reflect or otherwise alter the optical signals. In addition, fiber optic connectors for coupling optical fibers must be relatively rugged and adapted to be connected and disconnected a number of times in order to accommodate changes in the optical transmission path that may occur over time.
Although fiber optic connectors are most efficiently and reliably mounted upon the end portion of an optical fiber in a factory setting, many fiber optic connectors must be mounted upon the end portion of an optical fiber in the field in order to minimize cable lengths and to optimize cable management and routing. As such, a number of fiber optic connectors have been developed specifically to facilitate field installation. One advantageous type of fiber optic connector that is designed specifically to facilitate field installation is the UNICAM® family of field-installable fiber optic connectors available from Corning Cable Systems LLC of Hickory, N.C. Although the UNICAM® family of field-installable connectors includes a number of common features including a common termination technique (i.e., mechanical splice), the UNICAM® family also offers several different styles of connectors, including mechanical splice connectors adapted to be mounted upon a single optical fiber and mechanical splice connectors adapted to be mounted upon two or more optical fibers. Regardless, each such field-installable connector requires an apparatus for performing the splice termination and thereafter determining whether the continuity of the optical coupling between the field fiber and the stub fiber of the connector is acceptable. Typically, a splice termination is acceptable when a variable related to the optical performance of the connector, such as insertion loss or reflectance, is within a prescribed limit or threshold value.
Installation tools have been developed to facilitate the splice termination of one or more optical fibers to a fiber optic connector, and particularly, to enable the splice termination of one or more field optical fibers to a mechanical splice connector. Examples of conventional installation tools for performing mechanical splices in the field are described in U.S. Pat. Nos. 5,040,867; 5,261,020; 6,816,661; and 6,931,193. In particular, U.S. Pat. Nos. 6,816,661 and 6,931,193 describe a UNICAM® installation tool available from Corning Cable Systems LLC of Hickory, N.C., designed specifically to facilitate mounting the UNICAM® family of fiber optic connectors upon the end portions of one or more field optical fibers. Such an installation tool typically supports a mechanical splice connector, including a ferrule and the splice components, while a field optical fiber is inserted into the connector and aligned with a stub optical fiber. In this regard, the installation tool generally includes a tool base, a tool housing positioned on the tool base, and an adapter provided on the tool housing. The adapter has a first end for engaging the mechanical splice connector that is to be mounted upon the field optical fiber, and an opposed second end that serves as a temporary adapter. The forward end of the mechanical splice connector is received within the first end of the adapter, which in turn is positioned on the tool housing. The end portion of the field optical fiber is then inserted and advanced into the open rear end of the mechanical splice connector and the splice components are subsequently actuated, for example biased together by engagement of the cam member with at least one of the splice components, in order to secure the stub optical fiber and the field optical fiber between the splice components.
Once the fiber optic connector is mounted upon the end portion of the field optical fiber, the resulting fiber optic cable assembly is typically tested end-to-end for acceptable optical continuity. While optical connections and fiber optic cables are tested using a variety of methods, one widely accepted test includes the introduction of light having a predetermined intensity and/or wavelength into one of the stub optical fiber or field optical fiber. By measuring the light propagation through the fiber optic connector, or by measuring the amount of light emanating at the splice points, the continuity of the optical coupling can be determined.
In order to facilitate relatively simple, rapid and inexpensive continuity testing, Corning Cable Systems LLC of Hickory, N.C. has also developed installation tools for field-installable mechanical splice connectors that permit continuity testing while the connector remains mounted on the installation tool. In order to test the continuity of the optical coupling between the field optical fiber and the stub optical fiber, a light source is typically provided to the installation tool for delivering a visible wavelength (e.g., red) laser light to the optical fibers and the termination area. In known apparatus and methods, the visible light is delivered from the light source to the stub fiber through a jumper. The jumper typically includes a length of optical fiber having adapters mounted upon one or more ends of the fiber. As a result, the termination area is illuminated with visible light that produces a “glow” indicative of the amount of light from the stub optical fiber being coupled into the field optical fiber. At least a portion of the connector is formed of a transparent or non-opaque (e.g., translucent) material, for example, the splice components and/or the cam member, so that the glow at the termination area is visible to the operator.
The Corning Cable Systems LLC method for verifying an acceptable splice termination described above is commonly referred to as the “Continuity Test System” (CTS) and the combined functionality of the visible light laser, jumper and test connector are commonly referred to as a “Visual Fault Locator” (VFL). In practice the method is generally sufficient for determining whether the majority of splice terminations are acceptable since the quality of the splice need not be maintained to a high degree of precision and the operator is typically highly-trained and experienced. However, the aforementioned apparatus and methods suffer several shortcomings. Specifically, the aforementioned methods require that an operator keep track of and utilize numerous components, i.e., the jumper, adapter and test connector, in order for the system to properly function. A failure of any of these components will result in a flawed testing process. Additionally, the costs associated with the manufacture and use of the named structural components is excessive.
In view of the aforementioned shortcomings, improved apparatus and methods for performing splice terminations and verifying the acceptance of the same are needed. Such apparatus and methods require that a simplified installation tool incorporating an improved VFL be provided. Further, such apparatus and methods require that the VFL include an integrated adapter having a lens thereon and being operable for receiving a mechanical splice connector, such that the connector may be optically coupled with the VFL. Accordingly, the provisions of incorporating the VFL into the installation tool, eliminates the need for jumpers, adapters and test connectors, thereby permitting less experienced operators to use the system. This results in a lower cost system and method of use. In addition, improved apparatus and methods are also needed to eliminate the subjectivity presently introduced by an operator when verifying an acceptable splice termination in a field-installable fiber optic connector, and to thereby correspondingly increase the accuracy of determining whether a particular splice termination is acceptable. Preferably, such apparatus and methods should accommodate existing field-installable fiber optic connectors, and more preferably, single fiber and multi-fiber field-installable mechanical splice connectors.